Effect of uniaxial compressive strain on the thermoelectric properties of two-dimensional HfNF

Abstract Two-dimensional transition metal nitride halides have shown promise in thermoelectric applications due to their low dimensionality, xcellent electron transfer properties, and quantum confinement of carriers. This study focuses on investigating the impact of uniaxial compressive strain on the stability,electronic and thermoelectric properties of monolayer HfNF through first-principles calculations. The research findings reveal that the semiconductor properties of monolayer HfNF remain unchanged under various strain conditions. Furthermore,the thermoelectric properties of monolayer HfNF materials are examined using Slack model and the Boltzmann transport theory under different strain conditions.
The findings indicate that applying uniaxial compressive strains at temperatures of 500 K, 700K, and 900 K increase the Seebeck coefficients of n-type and p-type HfNF, resulting in an enhanced power factor for the material. Specifically, the power factor of p-type HfNF under uniaxial compressive strain increased by 83%, with the ZT value reaching 2.01 at 900 K, which is approximately 40% higher than the ZT value without strain. These results suggest that strain can be utilized as a modulation method to enhance the thermoelectric prop erties of materials. Moreover, the study suggests that two-dimensional HfNF holds great promise for thermoelectric applications when subjected to uniaxial compressive strain.